Surgical staplers have been long known in the surgical arts as a quick and efficient way of joining or repairing tissue. Stapling has become an accepted alternative to suturing. In certain types of surgical procedures the use of surgical staples has become the preferred method of joining tissue, and, specially configured surgical staplers have been developed for these applications. For example, intra-luminal or circular staplers have been developed for use in a surgical procedure known as an anastomosis.
Circular staplers are well known in this art. Circular staplers useful to perform an anastomosis are disclosed in U.S. Pat. No. 5,104,025 which is incorporated by reference. A conventional circular stapler typically consists of an elongated shaft having a proximal actuating mechanism and a distal stapling mechanism mounted to the shaft. The distal stapling mechanism typically consists of a fixed stapling cartridge containing a plurality of staples configured in a concentric circular array. A round cutting knife is concentrically mounted in the cartridge interior to the staples. The knife is moveable in an axial, distal direction. Extending axially from the center of the cartridge is a trocar shaft. The trocar shaft is moveable, axially, with respect to the cartridge and elongated shaft. An anvil member is mounted to the trocar shaft. The anvil member has a conventional staple anvil mounted to it for forming the ends of staples. The distance between the distal face of the staple cartridge and the staple anvil can be controlled by an adjustment mechanism mounted to the proximal end of the stapler shaft. Tissue contained between the staple cartridge and the staple anvil is simultaneously stapled and cut when the actuating mechanism is engaged by the surgeon.
An anastomosis is a surgical procedure wherein sections of intestine are joined together after a connecting section has been excised. The procedure requires joining the ends of two tubular sections together to form a continuous tubular pathway. Previously, this surgical procedure was a laborious and time consuming operation. The surgeon had to precisely cut and align the ends of the intestine and maintain the alignment while joining the ends with numerous suture stitches. The development of circular staplers has greatly simplified the anastomosis procedure and also decreased the time required to perform an anastomosis.
When performing an anastomosis using a circular stapler, typically, the intestine is stapled using a conventional surgical stapler with double rows of staples being emplaced on either side of a target section (i.e., specimen) of intestine. The target section is typically simultaneously cut as the section is stapled. Next, after removing the specimen, the surgeon typically inserts the anvil head (anvil member) into the proximal end of the lumen, proximal of the staple line. This is done by inserting the anvil head into an entry port cut into the proximal lumen by the surgeon. On occasion the anvil head can be placed transanally, by placing the anvil head on the distal end of the stapler and inserting the instrument through the rectum. Typically the distal end of the stapler is inserted transanally. The surgeon then typically ties the proximal end of the intestine to the anvil shaft using a suture or other conventional tying device. Next, the surgeon cuts excess tissue adjacent to the tie and the surgeon attaches the anvil to the trocar shaft of the stapler. The surgeon then closes the gap between the anvil and cartridge, thereby engaging the proximal and distal ends of the intestine in the gap. The surgeon next actuates the stapler causing several rows of staples to be driven through both ends of the intestine and formed, thereby joining the ends and forming a tubular pathway. Simultaneously, as the staples are driven and formed, a concentric circular blade is driven through the intestinal tissue ends, cutting the ends adjacent to the inner row of staples. The surgeon then withdraws the stapler from the intestine and the anastomosis is complete.
In order to assist the surgeon in performing an anastomosis, various accessories have been developed for use with a circular stapler. One such type of accessory is known as an anvil bushing and is disclosed in U.S. Pat. No. 4,592,354. The anvil bushing disclosed in that patent consists of two flanges separated by a shank member. The shank member has a cylindrical pathway running therethrough. The diameter of the cylindrical pathway is sized so that the spool is in frictional engagement with the anvil shaft. The spool is used as a tissue attachment or retention means wherein intestine is sutured or tied about the spool, and, the intestine may be cut adjacent to the spool.
U.S. Pat. No. 4,665,917 discloses an improved intraluminal stapler having a clamping means disposed on the anvil shaft. The clamping means consists of a circular array of barbs extending outwardly to grasp the ends of the intestine.
Although conventional anvil bushings have many advantages and have proven to be beneficial when used with a circular stapler, it is also known that there are disadvantages associated with their use. The anvil bushings must be mounted by the surgeon or an assistant on the anvil shaft prior to use. It is often difficult to precisely position the bushings on the anvil shaft in an optimal position to facilitate tying. It is also known that the presence of the anvil bushing may increase the closing force necessary to position the anvil in proximity to the cartridge to effectively allow stapling and cutting. It is additionally known that it is sometimes difficult to locate the proximal edge of the anvil bushing when the surgeon attempts to cut the intestine. Furthermore, it is also known that the mucosa of the intestine is extremely slippery and that it is difficult to retain the intestine on a conventional anvil bushing.
Therefore, what is needed in this art are new devices for use with a circular stapler which facilitate the use of a circular stapler in an anastomotic procedure and eliminate the disadvantages of existing anvil bushings.
Accordingly, it is an object of the present invention to provide a tissue retention spring for an anastomotic procedure which can be precisely located on an anvil shaft during a surgical anastomotic procedure.
It is yet another object of the present invention to provide a tissue retention spring which decreases the force required to close an anvil by providing tissue and fluid venting.
It is yet a further object of the present invention to provide a tissue retention spring which facilitates tissue cutting.
It is still a further object of the present invention to provide a tissue retention spring which has enhanced tissue grasping and retention and which provides additional length to which tissue may be tied.